Solenoid with hinged core



March 13, 1956 R. w. BACH! ETAL 2738451 SOLENOID WITH HINGED CORE FiledHay 16, 1952 3 Shaun-Shea 1 March 13, 1956 v R. w. BAcHl E1' AL SOLENOIDWITH HINGED CORE 3 Sheets-Sheet 2 Filed May 16. 1952 March 13, 1956 R,w, BACH] ETAL 2,`738,451

SOLENOID WITH HINGED CORE Filed May 16, 1952 3 Sheets-Sheet 3 7| 3/72'MO/JM'OM' Fbprf W ECM/71 Hfird/UDY F 15/7121 United States Patent OSOLENOID WITH HINGED CORE Robert W. Baehi, Itasca, and Hardin Y. Fisher,Hillside,

Ill., assignors, by mesne assignrnents, to Controls Corporation ofAmerica, Schiller Park, Ill., a corporaion of Delaware Application May16, 1952, Serial No. 288,262

2 Claims. (Cl. 317-197) This invention relates to hinged core solenoidson the order of the alternating current solenoids forrning the subjectof the copending application of Robert W. Bachi, Serial No. 288,263filed May 16, 1952, now Patent No. 2,692,965, but has more particularreference to solenoids intended for direct current service.

It has been customary in the past to provide direct current solenoidswith a cylindrical armature or plunger slidable endwise through anopening in a magnetically permeablc frame and projecting into the hollowinterior of a winding embraced by the frame. In most instances it hasbeen necessary to provide cooperating 'coned surfaces on the inner endof the plunger and the frame carried stop engaged thereby in theattracted position of the plunger. The purpose of such coning is toprovide the greatest possible area of air gap between the plunger orarmature and its stop, in the retracted position of the plunger, and atthe same time reduce the effective length and the reluctance of the airgap so as to obtain maximum pull on the plunger in the retractedposition thereof.

Plungers or armatures for direct current solenoids of the type hereinconcerned are constrainedto back and forth reciprocatory motion in thewinding, and for this purpose a tubular non-magnetic armature guide isusually confined inside the winding to slidably receive the armature.Unless the guide is accurately made and carefully aligned With theconical surface of the armature stop, the conical surfaces of thearmature and stop will engage eccentrically before the armature reachesits fully attracted position. This condition of contact between thearmature and its stop, before final seating of the armature takes place,is also frequently encountered whenever the armature fits too loosely inits guide and the conical surfaces on the armature and stop haverelatively long tapers. Under these conditions, efiicient operation ofthe solenoid is impossible as vfriction between the conical surfaces ofthe armature and its stop may seriously reduce the pull of the armatureon the load connected therewith. The armature may even stick in apartally open position due to excessive friction brought about by theeccentric engagement between the conical surfaces on the armature andstop.

Moreover, if the armature guide does not hold the armature exactlycoaxial with its stop, which it cannot do as long as Operatingclearances for the armature must be provided in the guide, the armatureis drawn radially against one side of the guide along the entire lengthof the armature projeeting thereinto. In some cases the friction betweenthe armature and guide which results from such lateral shifting of thearmature in extended positions thereof can exceed the pull of thesolenoid itself. This tendency of the armature to Shift laterally intocontact With the side wall of the guide, of course, subjects thearmature to unbalanced radial magnetic forces which increase the frictonbetween the side of the armature and its guide proportionately to theamount of unbalance.

ICC

It is, therefore, the primary object of this invention to provide asolenoid especially suited for direct current service in which theobjections discussed above are eliminated so as to assure maximumtractive etfort of the armature in either the extended or attractedposition of the same.

In accordance with the foregoing object, it is one of the purposes ofthis invention to provide a direct current solenoid wherein the armatureis mounted to swing about an axis fixed with respect to the winding soas to enable a portion of the armature to move along a very accuratepath into the interior of the winding without the need for a guide suchas was forrnerly required for the armature. Consequently, frictiontending to oppose attraction of the armature can be held to a minimum bythe provision of a good pivot bearing for the armature.

More particularly it is a purpose of this invention to provide a directcurrent solenoid wherein the benefits of 'coning of the armature and thestator carried stop for the armature are achieved without the necessityof machinng conical surfaces on the armature and the stator. Accordingto this invention, this is achieved through the provision of a coreincluding a stator and an armature each comprised of a bank of fiatlaminae having pole portions thereon projecting into the opposite endsof the winding to occupy laterally adjacent overlapped positions insidethe winding in either the retracted or the attracted position of thearmature. These pole portions preferably are taperingly reduced towardtheir extremities to provide fiat opposing beveled surfaces on theiroverlapping sides. Though these beveled surfaces are functionalequivalents of the conventional conical surfaces employed in D. C.solenoids in the past, the fact that they are employed in a solenoidhaving a hinged armature makes it possible for the armature to have alonger work stroke and a higher initial pull than could be obtained in aconventional solenoid with the same coil length.

Due to the provision of the laminated magnetically permeable armatureand stator, therefore, it is also possible to have any desired degree oftaper on the pole portions without the necessity for machining them. Inother words, the tapercd pole portions which correspond to the coming ofthe plunger and stop of 'the conventional solenoid can be formed byassem'olia'7 stacks of fiat starnped armature and stator laminae each ofwhich has an integral pole portion thereon provided with the same degreeof taper along one edge.

A fuither purpose of this invention is to provide a direct currentsolenoid which will also operate Satisfactorily with alternatingcurrent. In this respect it is a more specific object of this inventionto provide the solenoid with a magneticaily permeable laminated corehaving a stator and an armature of the type described, both of which aremounted for pivotal motion with respect to the winding and have polefaces formed thereon to engage with one another both inside and outsideof the winding in the attracted position of the core parts to afford acompletely closed magnetic Circuit about the Winding. The purpose of theclosed magnetic Circuit is to insure against chattering of the coreparts in their attracted positions and to achieve maximum hold-in powerregardless of whether the winding is energized by direct or alternatingcurrent. It is to be understood, of course, that the core parts areprovided with laterally overlaping pole portions, projecting intoopposite ends of the winding and having a taperingly reduced crosssection, to assure a high initial pull on the armature. This type ofsolenoid is disclosed but not specifically claimed in the copendingapplication of Robert W. Bachi and Hardin Y. Fisher, Serial No. 270,921rfiled February 11, 1952,

and relating to an electromagnetically operated latch mechanism.

With the above and other objects in view, which will appear as thedescription proceeds, this invention resides in the novel construction,combination and ari'angcment of parts sabstantially as hereinafterdescribed and more particularly defined by the appended claims, it'beingunderstood that such changes in the precise embodiment of thehereindisclosed invention may be made as come within the scope of theclaims.

The accornpanying drat'ings illustrate several complete cxamples of thephysical embodiments of the invention constructed according to the bestmodes so far devised for the Practical application of the principlesthereof, and in which:

Figure 1 is a view of a solenoid cmbodying the principles of thisinvention, and showing the same partiy in section and partly inelevation;

Figure 2 is a cross section view taken through Figura l along the planeof line 2-2;

Figure 3 is a view similar to Figure l but showing a modified embodimentof the solenoid which is suitable rfor either A. C. or D. C. momentaryduty;

Figure Li is a view similar to Figure 3 showing a further slightlymodified form of the solenoid of this invention;

Figtu'e 5 is a view somewhat similar to Figure 4 but showing a stillfurther modified embodiment of the inv brackct 9 between the oppositeupright legs lt? thereof.

The coil 5 is received in opposite substantially rectangular holes 12 inthe legs W of the bracket and is secured thereto in any suitable manner(not shown) with the axis of the winding midway between and parallel tothe upright legs lltl of the bracket.

The stator 6 comprises a bank of fiat identical laminae secured fiatwisetogether as by rivets or other suitable fastening means (not shown),fiXedly mounted on the frame between the legs 1d thereof as by rivets 14passing through the bank of laminac with their ends fixed in the legs ofthe supporting bracket.

The stator overlies and substantially closes one end of the winding andhas a pole portion 16 thereon projecting into the hollow intei'ior ofthe winding to occupy the lower half thereof. duced in cross sectiontoward its extremity which lies near the opposite end of the winding.Though not essential, the pole portion 16 is shown as uniformly reducedin cross section toward its extrernity so asV to provide a flat beveledsurface 17 thereon facing the axis of the winding and disposed at anangle thereto. For the purposes of this invention, however, the surface17 may have lengthwise curvature.

lt is important to note that the pole portion 16 is enlarged at itsbase, as at 18, to substantially fill the adjacent end of the winding.The enlarged portion 18 is shown as projecting a short distance into thewinding from the stator, and it has a fiat pole face 19 thereon,adjacent to the base of the pole portion 16, and facing the opposite endof the winding, toward the armature. The pole face 19 is preferably,though not necessarily, normal to the axis of the winding.

The statcr is also provided with a lateral extension 20 projectingradially downwardly across the sdjacent end of the winding to one sidethereof. In the present case The pole portion is taperingly rethisextension is provided with a concave pole face 21 facing the pivot pin 8and concentric to the axis thereof.

The armature 7 is also comprised of a bank of identical laminae securedflatwise together by any suitable means such as rivets (not shown). Thearmature has a J-shaped configuration, as viewed in side elevation, andone of the legs 22 thereof is provided with an aperture 23 to snugly butrotatably receive the pivot pin 8 so that the armature is mounted forswinging motion with its other leg 243 arranged to travel inwardly andoutwardly of the adjacent end of the winding in an accurately definedpath.

In the retracted position of the armature shown, the bight portion 25thereof rests against a cushioned stop 26 carried by the supportingbracket while the pole portion irovided by the leg 24' of the armaturaextends part Way into the adjacent end of the winding to over-lie theeX- treinity of the pole portion 16 of the stator. The leg 24 'is alsotaperingly reduced in cross section toward its extremity to provide aflat beveled surface 28 on the inner side thereof. The surface 28, ofcourse, is disposed at such an angle that it will closely overlie thesurface 17 of the Stator pole portion 16 in parallel relationshipthereto but will not contact the same in the attracted position of thearmature. A fiat pole face 29 on the eX- tremity of the leg 24 andopposite the pole face 19 on the stator fiatwise engages the latter poleface at the end of the attraction stroke of the armature to define theatti'acted position thereof, as indieated in construction lines inFigure 1.

Thus it will be noted that in the attracted position of the armatnre,the pole portions 1d and 24 occupy laterally aojacent overlappingpositions inside the winding while the pole faces 19 and 29 have flatsurface to surface engagement with one another inside the winding andalong a plane substantially normal or crosswise of the axis of thewinding.

The extremity of the other leg 22 of the armature through which thepivot pin 8 passes is provided with a rounded surface 31 concentric tothe axis of the pin S spaced slightly from the concave surface 21 of thestator, so that these curved surfaces provide pole faces at all timesdeiining a small air gap between the core parts. This air gap, ofcourse, eliminates any tendency for residual magnetism in the coreelements to interfere with retraction of the armature followingde-energization of the winding. The actual retraction of the armature,as is usual, may be effected by the load connected to the armature. Theload may be attached to the armature as v by opposite apertured ears 33thereon forrned as extensions of the outer side plates of the bank ofarmature laminations, as shown, and located at any point on the armaturedistant from the pivot pin 8.

Alternatively, the load may be connected to a pin 34 anchored in thearmature and projecting to the exterior of the supporting bracketthrough a slot 35 in either or both of the legs 10 thereof. Anothersimple manner of transmitting the tractive etfort of the armature to aload would be to fix the pivot pin 8 to the armature and to extend thepin a distance beyond the bracket so as to enable the securement of alever or the like thereto.

The solenoid shown in Figure l and described hereinabove is designedpartcularly for direct current hold in service. For this type ofservice, existence of a small air gap in the magnetic Circuit around thewinding, provided by the core elements in the attracted position of thearmature, does not appreciably detract from the magnetic force holdingthe armature seated. It will also be observcd that, compared to theaxial length of the winding, the armature has a relatively longattraction stroke .id that it Will have especially good pull incharacteristics in its retracted position due to the close proximity ofthe pole portions of the armature and stator. Moreover though thebeveled surfaces 17 and 28 on the pole portions of the armature andstator are the equivalent of 5 the coned surfaces on the plunger andstop in the conventional direct current solenoid, these surfaces do notneed to be machined but can be produced on the core laminations at anydesired bevel or angle in a stamping operation to reduce the cost of themanufacture.

Obviously, a direct current solenoid like that shown in Figure 1 canalso be used for momentary duty without any difference in operation, butfor momentary energization it may be desirable to secure a cushioningpad to one of the pole faces 3t9 or 29 to achieve more quiet operation.The solenoid illustrated in Figure 3 is like that shown and describedbut not specifically claimed in the copending application of Robert W.Bachi and Hardin Y. Fisher, Serial No. 270,924 filed February 11, 1952;and differs from the Figure 1 solenoid chiefiy in that both the armatureand stator are mounted on a pivot pin 8'.

This solenoid is used primarily for the control of a door latch of thetype used on refrigerators and the like and is intended for momentaryenergization by either an alternating or direct current source. For thisreason the pole face 19' of the stator is provided with a cushioning pad33 of rubber or the like to be engaged by the pole face 29' of thearmature as the latter approaches its attracted position to cushion theimpact of the armature against the stator.

A large bumper 39 of rubber or the like is mounted on a portion of thesupporting bracket to engage the outer side of the stator, and thisbumper serves the double purpose of holding the stator against theadjaeent end of the winding and in cooperation with the pad 38 absorbsthe impact of the armature. A third rubber pad 40 is preferablyinterposed between a portion of the stator and the adjacent end of thewinding so that the latter will be protected against damage which mightresult from any recoil of the stator, such as in bouncng off its bumper39.

In common with the solenoid illustrated in Figure 1, the solenoid ofFigure 3 likewise employs a laminated magnetically permeable stator 42and a laminated magnetically permeable armature 43. Both have theiropposite side plates extended and pivotally mounted on the hinge pin 8'so that the armature may swing from the retracted position shown,defined by its engagement with a cushioning stop 45 carried by thesupporting bracket, to an attracted position seating against thecushioning pad 38 on the stator.

The stator pole portion 47, in this case, projects into the adjacent endof the winding to occupy a position in the upper half thereof, remotefrom the hinge pin 8'; and it is taperingly reduced in cross sectiontoward its extremity to provide a fiat beveled surface 48 on itsunderside facing the aXis of the winding but disposed at an acute anglethereto. The cooperating pole portion 50 of the armature is disposedslightly closer to the axis of the hinge pin 8' and has its uppersurface 51 slabbed off and beveled to mesh with that of the stator as ittravels beneath the stator pole portion in the attraction stroke of thearmature.

Though the stator is also supported for pivotal motion on the hinge pin8' such pivotal motion thereof is limited by its confinement between therubber bumpers 39 and 40 to only that slight amount of motion which isrequired to absorb the impact of the armature thereagainst duringseating of the armature.

For controlling a door latch such as that disclosed in the copendingapplication of Robert W. Bachi and Hardin Y. Fisher, Serial No. 270,924filed February ll, 1952, the opposite side plates of the armature areextended beyond the axis of the hinge pin 8' and provide a lever 53 bywhich the tractive force of the armature may be applied to the latchmechanism. In the specific case shown the lever 53 carries a pin 54having a camming roller 55 freely rotatably mounted thereon to controlthe latch mechanism.

The armature 43 is also biased under substantial force to its retractedposition engaged with the cushioned stop 45 by means of a relativelyheavy torsion spring 57 en-V circling the bushing 58 on the hinge pin 8'by which the armature is mounted on the hinge pin. The torsion springhas one end 59 hooked over an adjacent edge of one of the armature sideplates, and has its opposite end portion 60 engaged with a stop 61carried by the supporting bracket. As disclosed in said copendingapplication, Serial No. 270,924, the lever 53, camming roller 55, andthe torsion spring may in effect form part of the latch mechanism to becontrolled.

Portions of the stator and armature adjacent to the hinge pin 8' alsohave opposing fiat pole faces 63 and 64, respectively, formed thereoneach lying in a plane radial and parallel to the axis of the hinge pinand which pole faces may engage one another flatwise or at least bebrought very close together as the armature seats to provide a goodmagnetic circuit around the winding through the core therefore.

The solenoid illustrated in Figure 4 is in most respects similar to thatshown in Figure 3 but is designed to permit flat intimate engagementbetween the pole faces 29' and 18' on the armature and stator,respectively, inside of the winding, while the external pole faces 63and 64 may come close together without actually engaging one another. Inthis case, the cushioning pad 38 used with the previous embodiment ofthe invention is eliminated, and accordingly the solenoid is bettersuited for hold in duty. If the solenoid of Figure 4 is to be used withalternating current, shading rings (not shown) can be imbedded in thepole faces 19' and 63 of the stator. The torsion spring 57 in this casecan be considered strong enough to retract the armature against theforces of residual magnetism existing in the core followingde-energization of the winding.

The solenoid shown in Figure 5 is substantially identical to that shownin the copending application of Robert W. Bachi, Serial No. 288,263,filed May 16, 1952. The main difference resides in the provision of poleportions 16' and 24' on the stator and armature, respectively,projecting into the opposite ends of the winding similarly to the poleportions on the core parts of the Figure 1 solenoid, to occupy laterallyadjacent overlapping positions inside the winding upon energizationthereof. Both the stator and the armature are rnounted for swingingmotion in response to energization of the winding, but while thearmature swings about a hinge pin 8' located exteriorly of the windingto one side thereof as in Figure 1 embodiment, the stator is mounted toswing about another pivot pin 66 having its ends received in theopposite legs of the supporting bracket and passing through the bank ofstator laminations to mount the same for swinging motion about an axisparallel to that of the hinge pin 8' but closely adjacent to the axis ofthe winding 5.

Consequently, the lower depending end or extension of the stator canswing toward the extension or exterior leg of the U-shaped armature tobring a flat pole face 67 on the stator extension into intimateengagement with a cooperating fiat pole face 68 on the adjacent leg ofthe armature in the attracted position of the core parts. in thismanner, the pivoted leg of tse armature provides a stop to limit theattraction stroke of the stator, while the pole face 19' of the statorprovides a stop substantially interposed between the stator hinge 66 andthe pole face 29' on the extremity of the armature pole portion to limitthe attraction stroke of the armature and define the attracted positionthereof.

Attention is directed to the fact that the envagement of the armaturepole portion 24' with the stator takes place inside the winding at alocation so related to the position of the hinge pin 66 for the stator'that practically no torsional forces are exerted upon the stator inconsequence of seating of the armature thereagainst.

Since the armature and stator have pole faces which will intimatelyengage with one another both inside and outside the Winding to provide acompletely closed magnetic circuit about the winding, it is also afeature of this invention that the effects of residual magnetisrn may beovercorne following de-energization of the Winding by a force suppliedto one of the two movable elements of the core without in anywiselessening the pull of the armature or creating resistance to swingingmotion 'diereof in its attraction stroke. This may be accomplished byinterposing a compression spring 7-3 between a finger '71 depending fromthe lower portion of the stator and a stop '72 on the supportingbracket, the spring having a force great enough to separate the polefaces 67 and 6%* and break the magnetic circuit about the winding at apoint exteriorly thereof following de-energzation of the winding. Thebiasing force of the spring exe'rted upon the stator, of course, makesit necessary to limit motion of the stator away from the armature andthis is accomplished in a simple manner by providing a resilient stop onthe supporting bracket adjacent to the outer curved surface of thestator to be engaged thereby under the infiuence of the biasing spring70 whenever the Winding is in a deenergized condition.

Although the provision of the tapered pole portions 16' and 24' on thestator and armature respectively, ideally adapt the solenoid of Figurefor D. C. service, it can also perform especially well with alternatingcurrent, iu which case shading rings (not shown) may be imbedded in thepole faces 19' and 67 of the stator to improve the hold incharacteristics of the solenoid.

From the foregoing description taken together With the accompanyingdrawings it will be readily seen that this invention provides a solenoidfeaturing isimplicity of construction through the elirnnation ofarmature guides, and wherein the laminated construction of the armatureand stator makes it possible for the first time to achieve coning andimproved traction characteristics in a D. C. solenoid without thenecessity of machining these surfaces; and that though primarilyintended for direct current service, this invention provides a solenoidwhich may be operated by either direct current or alternating currentwith increased efficiency.

What we claim as our invention is:

1. A solenoid comprising: a supporting bracket; an

annular winding carried by the supporting bracltet; a laminatedmagnetically permeable stator mounted on the supporting bracketalongside one end of the winding; a laminated magnetically permeablearmature mounted on the supporting bracket alongside the other end ofthe winding and movable along a defined path toward the stator to anattracted position in response to energization of the winding; elongatedcooperating pole portions on the armature and stator formed asextensions of the laminae thereof and projecting lengthwise into theopposite ends of the winding to occupy laterally adjacent overlappingpositions inside the winding in the attracted position of the armature;and cooperating abutments on the armature and stator engageable todefine the attracted position of the armature, the engaging surfaces ofsaid abutrnents providing pole faces disposed substantially crosswise ofsaid path along which the armature travels, and said abutments einglocated on the armature and stator pole portions and engaging oneanother inside the wiuding so that magnetic fiux is led uninterruptedlythrough the center of the winding in the attracted position of thearmature.

2. The solenoid set forth in claim 1 Wherein the laterally adjacentsides of said pole portions on the armature and stator havesubstantially flat angular surfaces tapering from a larger cross sectionadjacent to the bases of the pole portions to a smaller cross section atthe extremites of the pole portions; and wherein one of said abutrnentsis provided by the extremity of one of said pole portions, and the otherabutment being located adjacent to the base of the other pole portion.

References Cited in the file of this patent UNITED STATES PATENTS851,663 Jackson Apr. 30, 1907 1,165,904 Reed Dec. 28, 1915 1,436,639Bindschedler Nov. 28, 1922 1,5S5,216 Tugendhat May 18, 1926 2,310,056Bendz Feb. 2, 1943 2,449,901 Kaiser Sept. 21, 1948

